Data on cancer patients diagnosed for 1973 were submitted to the NCI in January 1975. This first submission of data by participants in the SEER Program served a methodological purpose by identifying problems in obtaining uniform data and problems in editing, correcting and preparing data for analysis. By utilizing data from participants who had an established population-based reporting system, cancer incidence estimates for 1973 were derived for comparison with Third National Cancer Survey 1969-71 incidence. Program efforts have been devoted to quality control and training of personnel responsible for acquiring the basic data and to the development of up-to-date data processing procedures for maintaining and updating information on cancer patients at the regional registry level.